Setup Analysis Position: Play it through Computer vs. Computer

I would like to set up certain positions, and see how the computer responds playing both sides.  Is this possible on Chess.com?  If it is, I have not figured it out.  If not, what are my best options for this?  My main preferred computer is a Mac, but I also have a Windows laptop.

Thanks in advance.

You could download Arena at: http://www.playwitharena.com/?Welcome_to_Arena 

Get free engines, like Stockfish and its various derivatives - various fee engines also come with it as I recall - and do what you are looking at.

I have it and have ran many a tournament with set openings and differing time controls.

@Cornfed Thanks, I will try that.  I have an unexplored copy of Arena on the Windows laptop, and lament that it isn't available on my beloved iMac.  I definitely think it could be an interesting tool.